Polyolefins are of great use in industry and are materials from which many everyday products are made. When making polyolefins, drying the wet material as it exits a polymerization reactor in a steam heated flash line or transfer line is necessary (a so-called “transfer line dryer (TLD)). A TLD typically includes a section of pipe through which a material to be dried flows and that is at least partially surrounded by a jacket sufficient to contain steam or another heating liquid against the section of pipe for transferring heat to the section of pipe and so to a product stream to be dried that is present in the pipe. (A “steam jacket”) These systems are typically configured with a steam control system to adjust the steam feed rate to the entire transfer line steam jacket in order to control a temperature of a polymer product or gas temperature at the end of the dryer line or in a vessel at the end of the dryer. In many cases this control scheme is sufficient, but in the case of polyolefins with reduced melting points or reduced softening temperatures, the steam delivery rate or pressure of steam delivered to the transfer line must be controlled to ensure that the polyolefin product does not melt or soften. This control can be achieved by limiting the steam pressure to transfer line dryer steam jackets such that the inner walls of the transfer line dryer do not exceed a critical temperature associated with the melting or softening temperature of the polymer product. Such a steam pressure limitation or clamp often leads to a reduced capacity of the transfer line dryer which then leads to a process bottleneck resulting in reduced production rates or a need to increase the size or capacity of the transfer line to increase the throughput rates of the polyolefin production line.
Relevant publications include U.S. Pat. Nos. 8,597,582, 3,428,619, US 2008/127507, EP 2 110 173 A, and EP 1 914 247 A1.